Radical-mediated sulfonylation relay of alkyl alkynes/alkenes and electron-deficient alkenes to access vinyl and alkyl sulfones†

Achieving sulfonylation relay reactions between two distinct alkynes/alkenes remains a significant challenge due to inherent reactivity and selectivity issues. Herein, we report a radical-mediated sulfonylation relay of alkyl alkynes/alkenes and electron-deficient alkenes using Na₂S₂O₄ as a linker for the synthesis of highly selective (Z)-vinyl and alkyl sulfones. Notably, Na₂S₂O₄ serves not only as a convenient SO₂ source but also as an electron donor, obviating the need for metal catalysts and additional reductants typically required in conventional approaches. The protocol exhibits an excellent substrate scope and functional group tolerance, accommodating bioactive scaffolds with high efficiency. Mechanistic investigations revealed that the transformation proceeds via a radical pathway, with deuterium-labeling experiments confirming that the hydrogen atom in the protonation step predominantly originates from water.